Spin-lattice relaxation of the nuclear spin system in p-type GaAs is studied using a three-stage experimental protocol including optical pumping and measuring the difference of the nuclear spin polarization before and after a dark interval of variable length. This method allows us to measure the spin-lattice relaxation time T1 of optically pumped nuclei "in the dark", that is, in the absence of illumination. The measured T1 values fall into the sub-second time range, being three orders of magnitude shorter than in earlier studied n-type GaAs. The drastic difference is further emphasized by magnetic-field and temperature dependences of T1 in p-GaAs, showing no similarity to those in n-GaAs. This unexpected behavior is explained within a developed theoretical model involving quadrupole relaxation of nuclear spins, which is induced by electric fields within closely spaced donor-acceptor pairs.
@article{arxiv.1802.05013,
title = {Nuclear spin-lattice relaxation in p-type GaAs},
author = {M. Kotur and R. I. Dzhioev and M. Vladimirova and R. V. Cherbunin and P. S. Sokolov and D. R. Yakovlev and M. Bayer and D. Suter and K. V. Kavokin},
journal= {arXiv preprint arXiv:1802.05013},
year = {2018}
}